The clinical features, current methods of retinoblastoma in children are reviewed.

The clinical features, current methods of
diagnosis, and trends in management for
retinoblastoma in children are reviewed.
Nina Mikhailenko. Fall Day. Oil on canvas, 16″ × 20″.
Diagnosis and Management of Retinoblastoma
Carol L. Shields, MD, and Jerry A. Shields, MD
Background: Retinoblastoma is a highly malignant tumor of the eye that manifests most often in the first 3 years
of life.
Methods: Published articles were reviewed to evaluate the clinical features and current methods of diagnosis and
to assess the trends in management.
Results: This malignancy leads to metastatic disease and death in 50% of children worldwide but in less than 5%
of children in the United States and other developed nations with advanced medical care. Over the past decade, there
has been a trend away from enucleation and external beam radiotherapy and toward chemoreduction followed
by focal therapies. This is largely due to more effective chemotherapeutic regimens, improved focal treatment
modalities, and the desire to avoid loss of the globe and/or exposure to radiotherapy. Chemoreduction and focal
therapies are most successful for eyes with minimal to moderate retinoblastoma, with enucleation needed in less
than 15% of cases. Eyes with very advanced retinoblastoma require enucleation in approximately 50% of cases.
Conclusions: Progress in the clinical recognition and management of retinoblastoma has led to high survival rates.
Improved methods of treatment using chemoreduction and focal treatments without the need for external beam
radiotherapy allow preservation of the eye in some cases, often with visual function.
Introduction
Retinoblastoma is the most common intraocular cancer of
childhood.1,2 It represents approximately 4% of all pediatric
malignancies. It is estimated that 250 to 300 new cases of
retinoblastoma are diagnosed in the United States each year,
and 5,000 cases are diagnosed worldwide. Over 95% of
children with retinoblastoma in the United States and other
medically developed nations survive their malignancy,
whereas approximately 50% survive worldwide. This discrepancy is largely due to earlier detection in the United
States and developed nations when the tumor is contained
to the eye, whereas in underdeveloped regions, retinoblastoma is often detected after it has invaded the orbit or brain.
From the Ocular Oncology Service, Wills Eye Hospital, Thomas Jefferson
University, Philadelphia, Pennsylvania.
Submitted February 9, 2004; accepted June 8, 2004.
Address correspondence to Carol L. Shields, MD, Wills Eye Hospital,
Suite 1440, 840 Walnut Street, Philadelphia, PA 19107. E-mail:
[email protected]
No significant relationship exists between the authors and the companies/organizations whose products or services may be referenced in
this article.
Support for this article was provided by the Macula Foundation, New
York, New York, and the Eye Tumor Research Foundation, Philadelphia, Pennsylvania.
September/October 2004, Vol. 11, No. 5
Cancer Control 317
Genetics: Basic Facts
Retinoblastoma affects approximately 1 infant in 15,000 to
20,000 live births in the United States each year.1-3 Most
studies indicate that the incidence of retinoblastoma
among the various geographic populations is relatively
constant. The role of environmental influences in the
development of this malignant intraocular tumor remains
unclear. Prior to the 1860s, before the role of enucleation
in the management of retinoblastoma was known, most
cases of retinoblastoma proved fatal. At that time little was
suspected about the inheritance patterns of this tumor
because few patients, if any, survived to reproductive age.
Later, as more patients survived and had children of their
own, more evidence arose suggesting the hereditary
nature of retinoblastoma.4,5 It is now known that retinoblastoma can be inherited as a familial tumor in which the
affected child has a positive family history of retinoblastoma or as a nonfamilial (sporadic) tumor in which the
family history is negative for retinoblastoma. Approximately 6% of newly diagnosed retinoblastoma cases are
familial and 94% are sporadic. All patients with familial
retinoblastoma are at risk to pass the predisposition for
the development of the tumor to their offspring, but the
manifestations are only 80% penetrant.
Retinoblastoma is generally classified in three different
ways: familial or sporadic, bilateral or unilateral, and heritable or nonheritable.6 Clinically, we tend to use the first
two classification schemes.7 Thus, a case may be classified
as unilateral sporadic, bilateral sporadic, unilateral familial,
or bilateral familial. About two thirds of all cases are unilateral and one third are bilateral. Genetically it is simpler
to discuss retinoblastoma with the latter classification of
heritable or nonheritable. The three classification
schemes, however, are interrelated. It is recognized that
bilateral and familial retinoblastoma are caused by a
germline mutation and are thus a heritable tumor. Unilateral sporadic retinoblastoma is usually not heritable. However, it is estimated that approximately 10% to 15% of children with unilateral sporadic retinoblastoma have a
germline mutation. Genetic testing using DNA analysis of
the patient’s tumor and peripheral blood can help to identify those patients with germline mutation.8,9 The
retinoblastoma gene is located on the long arm of chromosome 13 (13q14). It is a large 4.73 kilobase message. An
intact gene protects against expression of retinoblastoma.
It is believed that the gene is a recessive suppressor gene
and may play a role in cell growth and development. In
order for retinoblastoma to develop, both copies of the
gene at the 13q14 locus must be lost, deleted, mutated, or
inactivated. If either the maternal or paternal copy of the
gene that is inherited by an individual is defective, then
that individual is heterozygous for the mutant allele. Tumor
formation requires both alleles of the gene to be mutant or
inactive. These two mutations correlate to the two “hits”
theorized by Knudson10 In 1971, he proposed the “two
318 Cancer Control
hit” hypothesis to explain the events that are necessary for
both heritable and nonheritable retinoblastoma. His theory was based on a comparative analysis of unilateral and
bilateral retinoblastoma cases. He proposed that the development of any retinoblastoma was caused by two complementary chromosomal mutations. Each of these genetic
events could occur randomly with a frequency of 2 × 107
per year. In the case of familial retinoblastoma, the initial
event or “hit” was a germinal mutation that was inherited
and found in all cells of the offspring. The second “hit”
occurred sometime during development, and if it occurred
in a somatic cell, such as a retinal cell, then retinoblastoma
would develop. Therefore, in familial cases of retinoblastoma, all cells in the body are predisposed to possible
tumor development since germline mutation (“first hit”)
has been inherited in all cells of the body, including the
ovaries and testes. This may help to explain the high incidence of second nonocular tumors, such as osteosarcoma,
seen in patients with familial retinoblastoma or bilateral
sporadic retinoblastoma. The offspring in cases of familial
retinoblastoma will likewise be predisposed because their
germinal mutation will be passed on. By contrast, in most
cases of unilateral sporadic retinoblastoma, the “two hits”
occur during development of the retina and both “hits” are
somatic mutations. The rest of the body theoretically carries no higher risk to develop other tumors because these
patients presumably have normal chromosomal structure
elsewhere in the body.
Genetics: 13q Deletion Syndrome
The retinoblastoma gene is located on the long arm of
chromosome 13 (13q). The 13q deletion syndrome can
manifest by several phenotypic abnormalities.6,8,9 Many
patients have minimal or no visible abnormality.10 The
characteristic findings include some degree of the following dysmorphic features: microcephaly, broad prominent
nasal bridge, hypertelorism, microphthalmos, epicanthus,
ptosis, protruding upper incisors, micrognathia, short neck
with lateral folds, large, prominent, low-set ears, facial
asymmetry, imperforate anus, genital malformations, perineal fistula, hypoplastic or absent thumbs, toe abnormalities, and psychomotor and mental retardation.11,12 The
midface of patients with 13q deletion is notable for prominent eyebrows, broad nasal bridge, bulbous tipped nose,
large mouth, and thin upper lip (Fig 1). We reported a
case of severe midline facial and central nervous system
abnormalities in a child with 13q abnormalities that manifested retinoblastoma and holoprosencephaly.9
Karyotype analysis of children with these or other
dysmorphic features may allow earlier detection of
retinoblastoma. We have seen several cases of retinoblastoma that were initially suspected based on the recognition of the above dysmorphic features that prompted a
karyotype analysis revealing a deletion in chromosome 13.
September/October 2004, Vol. 11, No. 5
This finding subsequently prompted a retinal examination
that revealed unilateral multifocal tumors in both cases.12
Life-Threatening Problems
Children with retinoblastoma are at risk for three important, life-threatening problems including metastasis from
retinoblastoma, intracranial neuroblastic malignancy (trilateral retinoblastoma), and second primary tumors.
At Risk for Metastasis
Retinoblastoma metastasis, when it occurs, generally
develops within 1 year of the diagnosis of the intraocular
tumor. Those at greatest risk for metastasis show features
of retinoblastoma invasion beyond the lamina cribrosa in
the optic nerve, in the choroid (>2 mm dimension), sclera,
orbit, or anterior chamber.13 Eyes with invasion of the
optic nerve or choroid generally demonstrate large
retinoblastoma over 15 mm greatest dimension along with
elevated intraocular pressure and total retinal detachment.14,15 Patients with evidence of invasive retinoblastoma should be treated with chemotherapy for 4 to 6
months to prevent metastases; however, criteria for
regarding the need for adjuvant chemotherapy remain
unclear. In an analysis from our department, metastases
were reduced from 24% in those without preventive
chemotherapy to 4% in those with chemotherapy.13
A
B
Fig 1. — Child with 13q syndrome. (A) Sixteen-month-old child with
manifested developmental delay and characteristic facies of 13q deletion
syndrome. (B) Unilateral retinoblastoma was later discovered in this patient.
The tumor was successfully treated with plaque radiotherapy.
September/October 2004, Vol. 11, No. 5
At Risk for Neuroblastic Intracranial Malignancy
(Trilateral Retinoblastoma)
There is an association of neuroblastic intracranial malignancy in patients with the hereditary form of retinoblastoma, most often manifesting as pineoblastoma or other
parasellar tumors.16 The pineoblastoma is identical to
retinoblastoma from an embryologic and pathologic
standpoint.16-19 This association of midline intracranial
pineal tumors and suprasellar/parasellar neuroblastic
tumors with bilateral retinoblastoma has been termed
trilateral retinoblastoma.20 Loss of function of the retinoblastoma gene is believed to confer an increased susceptibility to developing these intracranial tumors. Trilateral
retinoblastoma is found in approximately 3% of all children with retinoblastoma.18,19 Those patients with bilateral or familial disease are at greatest risk, with 5% to 15%
developing this finding.18,19 Hence, patients with bilateral
or familial retinoblastoma are advised to have screening
for pineoblastoma using computed tomography or magnetic resonance imaging of the brain twice yearly for the
first 5 years of life. In some cases, the intracranial tumor
preceded the diagnosis of retinoblastoma.18 It is possible
that many cases of pineoblastoma were previously misinterpreted as metastatic retinoblastoma to the brain. Unlike
other second tumors, the pineoblastoma usually occurs
during the first 5 years of life,19 whereas second tumors
often take many decades to develop. Unfortunately,
pineoblastoma is usually fatal. The possibility of pineoblastoma should be included in the genetic counseling of
patients with hereditary retinoblastoma. Newer evidence
suggests that recent treatment methods of systemic
chemoreduction for retinoblastoma may prevent trilateral
retinoblastoma.21 In a study of 100 patients with hereditary retinoblastoma, trilateral retinoblastoma was found in
no patient who received chemoreduction and it would
have been expected in 5 to 15 patients. Thus, prevention
of trilateral retinoblastoma may be possible with neoadjuvant chemotherapy.
At Risk for Second Primary Tumors
Another important aspect of genetic counseling concerns
the development of new genetically related cancers in survivors of bilateral or heritable retinoblastoma. It is now
recognized that a child with retinoblastoma has approximately a 5% chance of developing another malignancy
during the first 10 years of follow-up, 18% during the first
20 years, and 26% within 30 years.22 The 30-year cumulative incidence is approximately 35% or even higher for
those patients who received radiation therapy (external
beam therapy) compared with an incidence rate of 6% for
those patients who avoided radiation. Therefore, patients
with bilateral retinoblastoma have an increased incidence
of second tumors, and this rate is further increased
in those treated with external radiation therapy.22
Osteogenic sarcoma, often involving the femur, is most
common, but other tumors such as spindle cell sarcoma,
Cancer Control 319
Fig 2. — Leukocoria in a child with advanced unilateral sporadic retinoblastoma.
chondrosarcoma, rhabdomyosarcoma, neuroblastoma,
glioma, leukemia, sebaceous cell carcinoma, squamous cell
carcinoma, and malignant melanoma have also been recognized. The mean latency period for the appearance of
the second primary is approximately 13 years.22 Patients
who survive a second tumor are at risk for a third, fourth,
and even fifth nonocular tumor.23
Clinical Features of Retinoblastoma
The clinical manifestations of retinoblastoma vary with the
stage of the disease at the time of recognition. In its earliest
clinical stage, a small retinoblastoma, ie, less than 2 mm in
basal dimension, appears ophthalmoscopically as a subtle,
transparent or slightly translucent lesion in the sensory retina.1,2 Slightly larger tumors lead to dilated retinal blood vessels that feed and drain the tumor. Some larger tumors
show foci of chalk-like calcification that resemble cottage
cheese. Any retinoblastoma of any size can produce leukocoria. The larger tumors more often present with this leukocoria (Fig 2). This white pupillary reflex is a result of reflection of light from the white mass in the retrolental area.
Retinoblastoma growth patterns are subdivided into
intraretinal, endophytic, and exophytic (Fig 3). Intraretinal
tumors are those listed above, limited to the substance of
the retina. Endophytic retinoblastoma is one that grows
from the retina inward toward the vitreous cavity. Hence,
it is characterized by a white, hazy mass with obscuration
of the retinal blood vessels. Because of its friable nature,
an endophytic tumor can seed the vitreous cavity and
anterior chamber and simulate endophthalmitis, especially toxocariasis, a parasitic disease found in young children.
A
B
Fig 4. — Enucleated globe with large retinoblastoma filling the vitreous cavity.
An exophytic retinoblastoma is one that grows from the
retina outward into the subretinal space. Such tumors produce a progressive retinal detachment, with the retina
often displaced anteriorly behind a clear lens (Fig 4). An
exophytic retinoblastoma can clinically resemble Coats’
disease or other forms of exudative retinal detachment.
Occasionally, a retinoblastoma can assume a diffuse infiltrating pattern, characterized by a relatively flat infiltration
of the retina by tumor cells without an obvious mass. In
such cases, the diagnosis may be more difficult, and this
pattern can simulate uveitis or endophthalmitis. Less frequently, the presenting feature can be pseudohypopyon
due to tumor seeding in the anterior chamber, hyphema
secondary to iris neovascularization, vitreous hemorrhage,
or signs of orbital cellulitis.
Classification of Retinoblastoma
Several classifications of retinoblastoma have been developed to assist in prediction of globe salvage. The most
popular grouping is the Reese-Ellsworth classification
(Table 1).24 A new International Classification of Retinoblastoma is currently being developed to simplify the
grouping scheme and allow a more practical approach to
judging results of chemoreduction.25
C
Fig 3. — Variations in the appearance of retinoblastoma. (A) Intraretinal retinoblastoma. (B) Endophytic retinoblastoma. (C) Exophytic retinoblastoma.
320 Cancer Control
September/October 2004, Vol. 11, No. 5
Table 1. — Reese-Ellsworth Classification for
Conservative Treatment of Retinoblastoma*
Group I: Very favorable
(a) Solitary tumor, less than 4 disc diameters in size, at or
behind the equator
(b) Multiple tumors, none over 4 disc diameters in size, all at
or behind the equator
Group II: Favorable
(a) Solitary tumor, 4 to 10 disc diameters in size, at or
behind the equator
(b) Multiple tumors, 4 to 10 disc diameters in size,
behind the equator
Group III: Doubtful
(a) Any lesion anterior to the equator
(b) Solitary tumors larger than 10 disc diameters
behind the equator
Group IV: Unfavorable
(a) Multiple tumors, some larger than 10 disc diameters
(b) Any lesion extending anteriorly to the ora serrata
Group V: Very unfavorable
(a) Massive tumors involving over half the retina
(b) Vitreous seeding
* Refers to chances of salvaging the affected eye and not systemic
prognosis.
Differential Diagnosis
A number of ocular disorders in infants and children can
clinically resemble retinoblastoma.26 Despite the classic
appearance of retinoblastoma, nearly 50% of patients diagnosed initially with possible retinoblastoma prove, on referral to ocular oncologists, to have simulating conditions and
not retinoblastoma.27 The most common pseudoretinoblastomas include persistent hyperplastic primary vitreous,
Coats’ disease, and ocular toxocariasis (Table 2). Therefore,
it is important that the diagnosis of retinoblastoma be established without question prior to beginning treatment. Consultation with ocular oncologists experienced with
retinoblastoma may be helpful in confirming the clinical
diagnosis of retinoblastoma and assisting in designing a
management plan for this potentially fatal disease.
Diagnostic Testing
Accurate diagnosis in a child with suspected retinoblastoma is accomplished by taking a detailed history, physical
evaluation, external ocular examination, slit lamp biomicroscopy, and binocular indirect ophthalmoscopy with
scleral indentation. This is generally performed either in
the office or under anesthesia in order to determine precisely the number and location of all tumors. The diagnosis is established by the classic appearance of the retinal
tumors by an experienced examiner. Needle biopsy confirmation is rarely, if ever, necessary. Ancillary diagnostic
studies can be helpful in confirming the diagnosis of
retinoblastoma. Fluorescein angiography shows early vascularity and late hyperfluorescence of the tumor. Ultrasonography and computed tomography can demonstrate
September/October 2004, Vol. 11, No. 5
the intraocular tumor and possibly detect calcium within
the mass. Approximately 5% to 10% of retinoblastomas
show no intrinsic calcification. Magnetic resonance imaging does not usually detect calcium but may be of value in
the assessment of the optic nerve, orbit, and brain. Optic
coherence tomography has been found useful in the
detection of cystic retinoblastoma that might show less
dramatic response to chemotherapy, and it is also helpful
in the follow-up of patients to assess macular anatomy.27
If a clinician who is not entirely familiar with
retinoblastoma is contemplating use of chemoreduction
for a child with possible retinoblastoma, or even a needle
biopsy or diagnostic vitrectomy, we recommend that the
clinician consult with an experienced ocular oncologist
before continuing with the procedure.
Management of Retinoblastoma
The most important objective in the management of a
child with retinoblastoma is survival of the patient, and
the second most important goal is preservation of the
globe. The focus on visual acuity comes later, after safety
of the patient and globe is established. Therapy is tailored
to each individual case and based on the overall situation,
including threat of metastatic disease, risks for second cancers, systemic status, laterality of the disease, size and locaTable 2. — Conditions Closely Simulating Retinoblastoma in an
Analysis of 212 Pseudoretinoblastomas
Condition
Persistent hyperplastic primary vitreous
Coats’ disease
Ocular toxocariasis
Retinopathy of prematurity
Combined hamartoma
Coloboma
Vitreous hemorrhage
Astrocytic hamartoma
Familial exudative vitreoretinopathy
Bilateral retinal vascular hypoplasia with
persistent primary vitreous
Rhegmatogenous retinal detachment
X-linked retinoschisis
Medulloepithelioma
Congenital cataract
Retinal capillary hemangioma
Circumscribed choroidal hemangioma
Diffuse choroidal hemangioma
Peripheral uveoretinitis
Toxoplasmic retinitis
Idiopathic endophthalmitis
Norrie’s disease
Incontinentia pigmenti
Morning glory disc anomaly
Percentage of
Other Diagnoses
28
16
16
5
4
4
4
3
2
2
2
2
2
2
1
1
1
1
1
1
<1
<1
<1
Adapted from Shields JA, Parsons HM, Shields CL, et al. Lesions
simulating retinoblastoma. J Pediatr Ophthalmol Strabismus.
1991;28:338-340. Reprinted with permission by Slack, Inc.
Cancer Control 321
Table 3. — Chemoreduction Regimen for Intraocular Retinoblastoma
Given for a Total of 6 Monthly Cycles
Day
Vincristine
Etoposide
Carboplatin
×
×
×
0
1
×
Vincristine: 0.05 mg/kg
Etoposide: 5 mg/kg
Carboplatin: 18.6 mg/kg
tion of the tumor(s), and estimated visual prognosis. There
are several options for treatment of retinoblastoma, and the
ocular oncologist should be thoroughly familiar with the
indications, technique, and expected results of all treatment methods as well as the expected systemic and visual
problems. The currently available treatment methods for
retinoblastoma include intravenous chemoreduction
(sometimes combined with subconjunctival chemoreduction), thermotherapy, cryotherapy, laser photocoagulation,
plaque radiotherapy, external beam radiotherapy, enucleation, orbital exenteration, and systemic chemotherapy for
metastatic disease.1,2,7,28 In recent years, eyes with unilateral retinoblastoma are generally managed with enucleation if the eye is classified as Reese-Ellsworth group V; for
those eyes in groups I to IV, chemoreduction or focal measures are used. For bilateral retinoblastoma, chemoreduction is utilized in most cases unless there is extreme asymmetric involvement, with one eye having advanced disease
necessitating enucleation while the other eye has minimal
disease, treatable with focal methods. Most children with
bilateral retinoblastoma are treated with chemoreduction
for at least one of their two involved eyes.
A
B
Fig 5. — Regression of macular retinoblastoma following chemoreduction
and focal foveal-sparing thermotherapy. (A) Before treatment. (B) After
treatment, the tumor has remained regressed without recurrence at 4 years.
reported that the retinoblastomas decreased a mean of
35% in tumor base and nearly 50% in tumor thickness after
2 cycles of chemoreduction.34 Subretinal fluid resolved in
76% of cases and both vitreous and subretinal seeds
showed regression with the treatment.35 Thus, it is apparent that retinoblastoma is sensitive to current chemoreduction regimens.
Ocular salvage rates have improved with the addition
of chemoreduction to treatment regimens (Table 4).36-38
Following the initial observations on the usefulness of
chemoreduction by Kingston et al,31 we found that
chemoreduction permitted globe salvage in 85% of eyes
classified as Reese-Ellsworth groups I to IV and 47% of
those classified as group V, but some of the advanced eyes
required external radiotherapy for salvage (Table 5).38
The main problem with chemoreduction is recurrence of related vitreous or subretinal seeds, usually
remote from the main tumors (Table 6).39,40 These seeds
generally respond to initial chemoreduction but later they
can recur. Recurrent seeds are generally detected within
the first 2 years after chemoreduction. Active subretinal
and vitreous seeds require treatment, and it is important to
recognize them early as treatment modalities are limited.
Additionally, it should also be realized that 24% of patients
develop new retinoblastomas during or after chemoreduction, mostly in those who present as infants and with
family history of retinoblastoma.41
Chemoreduction
Chemoreduction is a method of reducing tumor volume to
allow for therapeutic measures that are more focused and
less damaging.29 It has evolved to be an important measure in the initial management of retinoblastoma.30-34 The chemotherapeutic agents vary
Table 4. — Comparison of Globe Salvage Rate Using
External Beam Radiotherapy Alone, External Beam Radiotherapy
depending on the preference of the pediatric
Plus Salvage Treatment, and Chemoreduction Plus Focal Adjuvant Treatment
oncologist. We presently use carboplatin,
etoposide, and vincristine (Table 3). Other
Reese-Ellsworth Group
Globe Salvage
oncologists include only one agent (carboEBRT Alone
EBRT + Salvage Treatment
CRD + AT
platin) or two agents (vincristine, carboplatin)
Ellsworth et al36
Hungerford et al37
Shields et al38
in their protocol. The chemotherapy regimen
1965-1972
1970-1985
1994-2001
is generally given for 6 cycles to allow for adeI
91%
100%
100%
quate tumor reduction. Focal therapy to the
II
83%
84%
93%
individual tumors is delivered at cycle 2 after
III
82%
82%
100%
achieving adequate tumor reduction and subIV
62%
43%
74%
retinal fluid resolution. The objective of
V
29%
66%
47%
chemoreduction is to reduce tumor size so
EBRT - external beam radiotherapy
that focal treatments can be applied to a
CRD - chemoreduction using vincristine, etoposide, and carboplatin
smaller tumor volume in order to preserve
AT - adjuvant treatment (laser photocoagulation, cryotherapy, thermotherapy,
more vision and possibly avoid enucleation
plaque radiotherapy, external beam radiotherapy)
and external beam radiotherapy (Fig 5). We
322 Cancer Control
September/October 2004, Vol. 11, No. 5
those treated with chemoreduction plus thermotherapy, cryotherapy, or both showed recurrence in only 22% by 7 years (Table 7). This sugReese-Ellsworth Group
Kaplan-Meier Estimates of Probability of Enucleation
gests that tumor consolidation following
chemoreduction is the best approach to preAt 1 year
At 3 years
At 5 years
vent ultimate recurrence. However, this is not
(probability ± SE) (probability ± SE) (probability ± SE)
I
0.00 ± 0.00
0.00 ± 0.00
0.00 ± 0.00
always possible as some tumors are located in
(n = 0 of 9 eyes)
the central fovea, and consolidation would comII
0.00 ± 0.00
0.07 ± 0.06
0.07 ± 0.06
promise visual acuity. In these cases, we make
(n = 1 of 26 eyes)
every effort to avoid consolidation or provide
III
0.00 ± 0.00
0.00 ± 0.00
0.00 ± 0.00
foveal-sparing thermotherapy.43,44
(n = 0 of 16 eyes)
Overall, chemoreduction is an effective iniIV
0.07 ± 0.05
0.15 ± 0.09
0.26 ± 0.13
(n = 4 of 32 eyes)
tial measure for selected children with retinoblasI-IV
0.03 ± 0.02
0.08 ± 0.04
0.15 ± 0.08
toma. Definitive focal therapy is important once
(n = 5 of 83 eyes)
tumor reduction is achieved from the
V*
0.23 ± 0.05
0.49 ± 0.07
0.53 ± 0.07
chemotherapy. The 6-cycle regimen that we
(n = 32 of 75 eyes)
employ might cause transient bone marrow supTotal groups I-V
0.13 ± 0.03
0.29 ± 0.04
0.34 ± 0.05
pression and a risk for infection.45 The risk for
(n = 37 of 158 eyes)
induction of second cancers exists and is not
* Chemotherapy included vincristine, etoposide, carboplatin for 6 cycles
known, but it is predicted to be minimal due
SE = standard error
Adapted from Shields CL, Honavar SG, Meadows AT, et al. Chemoreduction plus focal
to the short-term treatment period. Secondary
therapy for retinoblastoma: Factors predictive of need for treatment with external beam
leukemia is a concern in children who receive
radiotherapy or enucleation. Am J Ophthalmol. 2002;133:657-664. Reprinted with
high doses of etoposide. Other problems include
permission by Elsevier.
ototoxicity and nephrotoxicity. By using our
chemotherapy protocol in over 200 children
Only a few reports have addressed tumor control folwith retinoblastoma, we have not experienced any of these
lowing specific chemoreduction regimens for retinoblasserious side effects in our patients.
toma. Wilson et al39 used chemotherapy alone (vincristine
Subconjunctival Chemoreduction
and carboplatin) without tumor consolidation for 36 eyes
for Retinoblastoma
with retinoblastoma for eight cycles over 6 months. Complete tumor control was found in only 8% of eyes, whereChildren with advanced retinoblastoma in both eyes or in
as 92% showed recurrence of retinal tumor, subretinal
their only remaining eye are generally treated with
seeds, or vitreous seeds. We later evaluated individual consystemic chemoreduction and a local periocular boost
trol of retinal tumor, subretinal seeds, and vitreous seeds
of subconjunctival carboplatin. Animal models have
per treated eye.40 We treated 158 eyes with retinoblasshown that carboplatin penetrates the sclera into the
toma using vincristine, etoposide, and carboplatin for 6
vitreous cavity, allowing for effective higher dosages at
cycles over 6 months. All retinoblastomas, subretinal
that site.46-49 Initially, subconjunctival carboplatin alone
seeds, and vitreous seeds showed initial regression.
Tumor consolidation with thermotherapy or
Table 6. — Chemoreduction and Focal Treatment for Retinoblastoma in
158 Eyes of 102 Patients: Kaplan-Meier Estimates of Recurrence Per Eye of
cryotherapy following chemoreduction was proRetinal Tumor, Vitreous Seeds, and Subretinal Seeds
vided for each retinal tumor, but the vitreous and
subretinal seeds were treated with chemoreducFeature
Kaplan-Meier Estimates of Probability of an Event
tion alone without consolidation. The 5-year
At 1 year
At 3 years
At 5 years
Kaplan-Meier results showed that approximately
(probability ± SE) (probability ± SE) (probability ± SE)
50% of the eyes with vitreous seeds at presentation
Retinal tumor recurrence
0.37 ± 0.04
0.51 ± 0.05
0.51 ± 0.05
showed at least one vitreous seed recurrence, 62%
(n = 69 of 158 eyes)
of the eyes with subretinal seeds at presentation
Vitreous seed recurrence
0.26 ± 0.06
0.46 ± 0.08
0.50 ± 0.08
showed at least one subretinal seed recurrence,
(n = 21 of 54 eyes)
and at least one retinal tumor recurrence per eye
Subretinal seed recurrence
0.53 ± 0.06
0.62 ± 0.06
0.62 ± 0.06
was found in 51% of the eyes (Table 6).40 A more
(n = 40 of 71 eyes)
recent analysis of 457 consecutive retinoblasSE = standard error
tomas by our group has focused on individual
From Shields CL, Honavar SG, Shields JA, et al. Factors predictive of recurrence of
tumor control with chemoreduction with or withretinal tumor, vitreous seeds, and subretinal seeds following chemoreduction for
42
out focal tumor consolidation. Those tumors
retinoblastoma. Arch Ophthalmol. 2002;120:460-464. Copyright 2002, American
treated with chemoreduction alone showed recurMedical Association. All rights reserved.
rence in 45% by 7 years of follow-up, whereas
Table 5. — Chemoreduction Plus Focal Therapy for Retinoblastoma (N = 158 Eyes)
in 103 Consecutive Patients: Overview of Treatment Failure and Need for Enucleation
September/October 2004, Vol. 11, No. 5
Cancer Control 323
Table 7. — Chemoreduction for 457 Retinoblastomas in 193 Eyes of 125 Patients: Kaplan-Meier Estimates of Recurrence per Tumor
Chemoreduction Strategy
Kaplan-Meier Estimates
Recurrence of Retinoblastoma
at 1 year
at 2 years
at 3 years
at 4 years
at 5 years
at 6 years
at 7 years
Total
Chemoreduction
Alone
Chemoreduction Plus
Thermotherapy
Chemoreduction Plus
Adjuvant Therapy
Chemoreduction With or
Without Adjuvant Therapy
n = 63 tumors
n = 256 tumors
n = 394 tumors
n = 457 tumors
% failed*
% failed*
% failed*
% failed*
39%
45%
45%
45%
45%
45%
45%
[24 / 37]
[27 / 18]
[27 / 15]
[27 / 10
[27 / 10]
[27 / 10]
[27 / 8]
18%
20%
21%
22%
22%
22%
22%
[43 / 188]
[49 / 163]
[50 / 122]
[51 / 101]
[51 / 72]
[51 / 39]
[51 / 16]
13%
17%
17%
18%
18%
18%
18%
[50 / 309]
[61 / 258]
[62 / 191]
[64 / 153]
[64 / 99]
[64 / 57]
[64 / 31]
17%
20%
21%
22%
22%
22%
22%
[73 / 347]
[88 / 276]
[89 / 202]
[91 / 164]
[91 / 105]
[91 / 66]
[91 / 40]
* [# events / # still in risk set]
Adapted from Shields CL, Mashayekhi A, Cater J, et al. Chemoreduction for retinoblastoma. Analysis of tumor control and risks for recurrence in
457 tumors. In press. Reprinted with permission by Elsevier.
was tested for retinoblastoma control. However, retinoblastoma recurrence was inevitable, so currently the subconjunctival approach is combined with systemic
chemotherapy for best results. Toxicities include localized subconjunctival hemorrhage and pain, loss of limbal
stem cells with conjunctival overgrowth onto the cornea,
and orbital fibrosis with limited ocular motitlity.50
Focal Therapies
Focal therapies include laser photocoagulation, thermotherapy, cryotherapy, and plaque radiotherapy. Most of
these therapies are employed for small tumors, especially
those that have been reduced by chemoreduction. Commonly, focal therapies are applied to an eye while the child
is receiving chemoreduction, and they are repeated to
each tumor at each chemotherapy session. Plaque radiotherapy is generally reserved for tumors that fail other
focal therapies, even those that reach a moderate size, up
to 8 or 10 mm in thickness. The remainder of the focal
therapies are reserved for small tumors, generally those
under 3 mm in greatest dimension.
Laser photocoagulation is usually employed for small
retinoblastomas posterior to the equator of the eye. In
this era of chemoreduction, laser photocoagulation is
rarely employed as its success depends on vascular coagulation and tumor ischemia, whereas the opposite applies
to chemoreduction. Thus, it is not employed in eyes
receiving chemoreduction. Laser photocoagulation is
performed using the indirect ophthalmoscopic argon or
green diode laser with two rows of photocoagulation surrounding the tumor base and special effort to avoid direct
treatment to the tumor, which could lead to vitreous
seeding.51 Commonly, it is repeated at 1-month intervals
for three sessions.
Thermotherapy is a method of tumor heating using a
diode infrared laser system. It is usually performed in conjunction with chemoreduction or carboplatin alone so that
324 Cancer Control
the two techniques work in synergy to affect the tumor.
The goal is to deliver a temperature of 42ºC to 60ºC, a temperature that is below the coagulative threshold and thus
sparing the retinal vessels of photocoagulation. The combination of heat and chemotherapy is termed chemothermotherapy, and the combination of heat and radiation
is termed thermoradiotherapy. Heat has been found to
have a synergistic effect with both chemotherapy and radiation therapy for the treatment of systemic and ocular cancers.52 We employ thermotherapy as the main focal treatment to tumors following chemoreduction. The goal of
this treatment is to heat the tumor to a gray-white scar. In
general, small tumors require approximately 300 mW of
power for 10 minutes or less, and large tumors require up
to 800 mW of power for 10 minutes, each delivered over
three sessions at 1-month intervals.52
Thermotherapy coupled with chemoreduction is
especially suited for tumors adjacent to the fovea and
optic nerve where radiation or laser photocoagulation
would possibly induce more visual loss. It is a timeconsuming, tedious process that requires careful observations, recordings, judgments, and treatment of subtle
tumor findings. In addition, the cooperation of experienced facilities with pediatric oncologists, radiation
oncologists, ocular oncologists, and patient counselors is
essential for such a program.
Cryotherapy is useful in the treatment of equatorial
and peripheral small retinoblastomas.53 Tumor destruction is usually achieved with one or two sessions of triple
freeze-thaw cryotherapy delivered at 1-month intervals.
It is important to recognize that cryotherapy will usually
fail if there is overlying vitreous seeds. In these failed
cases, plaque radiotherapy is usually employed.
Cryotherapy remains an important method for tumor
consolidation following chemoreduction. It is a critical
modality for management of recurrent subretinal seeds
near the ora serrata.
September/October 2004, Vol. 11, No. 5
Plaque radiotherapy is a method of brachytherapy in
which a radioactive implant is placed on the sclera over the
base of a retinoblastoma to irradiate the tumor transsclerally. Generally, it is limited to tumors less than 16 mm in
base and 8 mm in thickness. It requires an average of 2 to
4 days of treatment time to deliver the total dose of 40 Gy
to the apex of the tumor. Plaque radiotherapy can be used
as a primary or secondary treatment.54,55 In fact, in 70% of
cases,plaque radiotherapy is used as a secondary treatment
to salvage a globe after prior failed treatment, usually failed
external beam radiotherapy or chemotherapy.54
Overall, using Kaplan-Meier estimates, there is approximately an 80% tumor control rate at 4 years with one
application of plaque radiotherapy.55 Carefully selected
retinoblastoma, even juxtapapillary and macular tumors,
can be successfully treated with plaque radiotherapy.
Retinoblastomas that are treated with plaque as a primary
treatment show tumor control in 88%, and control is similar (92%) following plaque of previously failed chemoreduction.55 Tumor control is poorer following plaque
of previous failed external beam radiotherapy (75%). The
visual outcome varies with tumor size and location as well
as radiation problems of retinopathy and papillopathy. The
visual outcome has been reported to be good in 62%, and
the measured vision was 20/20 to 20/30 in over half of the
cases.55 Radiation maculopathy is found in 25% of treated
eyes and papillopathy in 26% of eyes by 5 years.55
Innovations with custom design of plaques, especially
those for small tumor recurrences, have also assisted in
avoiding radiation retinopathy. Plaque radiotherapy has
not been associated with induction of second cancers,
likely due to its focal, shielded radiation field.
External Beam Radiotherapy
Retinoblastoma is generally a radiosensitive tumor. External beam radiotherapy is a method of delivering whole
eye irradiation to treat advanced retinoblastoma, particularly when there is diffuse vitreous seeding. Various treatment plans have been employed. The whole eye technique and lens-sparing technique were recently reviewed
by the group at St. Bartholomew’s Hospital in London.37,56
They found that the eye preservation rate had improved
markedly from reported older series, and the rate of ocular salvage depended on not only the stage of the disease
(Reese-Ellsworth stage) at the time of treatment, but also
the availability of focal therapy for limited recurrences.
Recurrence of retinoblastoma after external beam radiotherapy continues to be a problem that can develop within the first 1 to 4 years after treatment. Tumor recurrence
has also been found to be related to the stage of the disease and largest tumor size at the time of treatment.
Little has been written on the visual outcome after
external beam radiotherapy for retinoblastoma. Radiation
damage to the retina, optic nerve, and lens can be challenging to manage.57 In patients with macular retinoblastoma, the visual outcome has been found to be dependent
September/October 2004, Vol. 11, No. 5
on the size of the tumor and the degree of involvement of
the fovea.57 Superimposed amblyopia can pose a problem,
and patching therapy should be employed when there is
hope for vision.
External beam radiotherapy may induce a second cancer in the field of irradiation.58-60 The 30-year cumulative
incidence for second cancers in bilateral retinoblastoma
has been reported at 35% for patients who received radiation therapy compared with 6% for those who did not
receive radiation.59 Abramson and Frank61 found that
external beam radiotherapy increased the incidence of
second cancers in the field of radiation but did not stimulate second cancers outside the field of irradiation. Importantly, the risk for radiation-induced cancers has been
found to be dependent on patient age at the time of irradiation as well as other factors. Patients treated with
external beam radiotherapy who are younger than 12
months of age have a greater risk for second cancers than
patients over 12 months of age.61
Enucleation
Enucleation is a frequently used and important method for
managing retinoblastoma. If there is advanced disease
with no hope for useful vision in the affected eye or if
there is a concern of invasion of the tumor into the optic
nerve, choroid, or orbit, then enucleation is appropriate.
Those eyes with secondary glaucoma, pars plana seeding,
or anterior chamber invasion are also generally best managed with enucleation.
In a review of 324 consecutive cases of retinoblastoma managed on the Oncology Service at Wills Eye Hospital from 1974 to 1988, we found that unilateral
retinoblastoma was managed with enucleation in 96%
cases from 1974 to 1978, in 86% cases from 1979 to 1983,
and in 75% cases from 1984 to 1988.62 A similar decreasing trend was found with bilateral retinoblastoma. These
trends remain relatively stable today, with approximately
65% to 75% of unilateral sporadic retinoblastoma managed
with enucleation.63
The technique of enucleation is to gently remove the
eye intact without seeding the malignancy into the orbit.64
After the globe is removed, it is placed on a separate tray
and fresh tissue is harvested in the operating room for
DNA analysis, using a specific technique.65 The surgeon
must change sterile gloves after this step to avoid the risk
of tumor contamination into the child’s orbit.
Many years ago, an orbital implant was usually not
placed after enucleation for retinoblastoma because it interfered with palpation of the socket and clinical detection of
orbital tumor recurrence. More recently, with improved
knowledge of the behavior of retinoblastoma and its low
risks for local orbital recurrence, there is less hesitation for
placing an orbital implant. In addition, available orbital
imaging modalities of computed tomography and magnetic
resonance imaging allow detailed orbital evaluation,despite
the presence of an implant. The orbital implant provides a
Cancer Control 325
more natural cosmetic appearance of the patient’s artificial
eye, minimizing sinking of the prosthesis and enabling
motility to the prosthesis. There are several available orbital
implants, including polymethylmethacrylate sphere,
coralline hydroxyapatite, and polyethylene.
Conclusions
Retinoblastoma continues to be a challenge both diagnostically and therapeutically. It is important to first clearly
establish the correct diagnosis before embarking on therapy. Many factors enter into management decisions such
as patient age, tumor laterality, size, location, and extent,
and anticipated visual prognosis. Methods of chemotherapy have changed the approach to retinoblastoma in recent
years and have permitted many children to maintain their
eye(s) and avoid external beam radiotherapy. Enucleation
still proves to be useful for advanced tumor.
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